In many packaging processes the movement of the containers throughout the installation is performed intermittently due to the transformation processes (such as, for example, forming or sealing) which the receptacle experiences in the different stations or machines. This intermittent movement makes it difficult to efficiently load the products in the receptacles or containers since once the loading movement starts, the receptacle or container cannot advance until the loading has completed, causing idle time in the packaging process.
The products to be loaded generally arrive by a conveyor belt parallel to the loading station of the machine, in which it is increasingly more common to find robots loading the product in the housings of the container or receptacle. These robots grab a product or a group of products from said belts and deliver it in the housings of the previously formed container or receptacle. It is also common for the products to advance in the direction opposite to the advance of the receptacles (counter flow), although installations are also known in which the products advance in the same advance direction of the receptacles.
Currently, loading is performed with the container or receptacle stopped (in the pauses of the intermittent movement during which the forming, filling, sealing, cutting and extraction operations, among others, are performed in the subsequent parts of the machine) and the receptacle or container can comprise several housings which must be filled during the mentioned pause in the advance of the container. Thus, for example, if the receptacle to be filled has four housings and the manipulator has only been able to fill 3 of the 4 housings in the current cycle (pause of the intermittent movement) but has not had time to fill the fourth housing, the machine must delay its advance until the robot delivers the last product in the corresponding housing (for example in the fourth housing). This delay in the advance reduces productivity of the machine due to the accumulation of delay times.
To prevent these delays or idle times, there are alternatives based on the robot following the receptacle during its advance.
A solution to this problem consists of preventing the machine from remaining stopped until all the products have been loaded in their housings, making the manipulator move, following the housing to be filled during the advance of the machine and performing the loading with the moving receptacle. This is very common in continuous processes, for example, in the automotion sector.
However, in certain machines of the packaging sector, such as, for example, the thermoforming machines, no transformation conferring an added value to the receptacle/product is performed during the advance of the receptacles, therefore shifting from one station of the machine to another should be done as quickly as possible in order to eliminate these idle times. To that end, in these cases the advance speeds of the machine, and therefore of the receptacles, follow a very marked acceleration-deceleration curve. In this case the course taken by the robot while it follows a housing of the moving receptacle to deposit the product is very long since the robot will change its direction vector as it detects point-to-point the new positions of the housing. As a result, the manipulator will follow a curved path, seen in plan view, which means greater time and space traveled to reach the housing in which it will finally deposit the product, the case in which the robot reaches the housing once the advance has ended, or even later in very fast machines, possibly occurring. Therefore, in this case the course of the robot is not optimized and the excess time involves a reduction of the productivity of the robot.
The present invention seeks to optimize the productivity of the machine and to also optimize the excess time used by the robot to increase its productivity.